In the field of mobile communication, a small-scale base station defining a cell of a small area has been proposed in addition to a macro-cell base station defining a macro cell of which the radius is from a few hundred meters to a few kilometers (for example, see Patent Document 1). In particular, an extremely small cell in which the radius is about a few meters is referred to as a femto cell, and the base station defining a femto cell is referred to as a femto base station or a femto-cell base station. It is assumed that femto base stations will be placed in houses or small offices.
In a technique described in Patent Document 1, when a mobile station visits a femto cell, in order to prompt the mobile station to communicate by means of the femto base station, a frequency guiding device informs the mobile station of the frequency used in the femto base station so as to guide the mobile station to capture the frequency and connect to the femto base station. The femto base station uses a frequency differing from that used by the macro base station. According to the technique described in Patent Document 1, when the mobile station is in a region in which a macro cell and a femto cell overlap, the mobile station is guided to use the femto base station rather than the macro base station. Accordingly, radio resources of the femto base station can be used, for example, by a small number of mobile stations, and therefore, these mobile stations can benefit from higher communication rates.
In recent years, third generation (3G) radio access technology is in widespread use. On the other hand, studies have been proceeding with LTE (Long Term Evolution) in 3GPP (Third Generation Partnership Project). As of now, base stations that can use both the 3G and LTE radio access technologies for communicating with mobile stations have not been in practical use. However, it is possible to manufacture base stations that can use both the 3G and LTE radio access technologies for communicating with mobile stations, in theory. Such base stations would be able to communicate with both a 3G dedicated mobile station and an LTE dedicated mobile station. In addition, mobile stations that can use both the 3G and LTE radio access technologies (hereinafter, referred to as “dual-type mobile stations”) would be able to communicate with such base stations by using either one of the radio access technologies.